1. Field of the Invention
This invention relates generally to blow molding. In particular, this invention relates to apparatus and methods for heat transfer in mold components for blow molding.
2. Description of Related Art
Molds for blow molding articles having bases including concave portions are known wherein the molds comprise left and right mold halves and a base component. Further, it is known to provide passages within the mold members for conduction of heat transfer fluid to enhance temperature conditioning of the material from which the articles are formed. In this regard, it is known to use heat transfer fluid to remove heat from the material after expansion to the shape of the mold cavity to reduce the time required for the expanded article to become sufficiently solid for removal from the mold without unacceptable deformation. To effectively remove heat from the concave base of an article, it is known to provide conduction of heat transfer fluid proximate the molding surface of the base component of the mold. As a consequence of the required projection of the base component to form the concave portion of the molded article, the base component has a relatively large thermal mass. However, it is common that the molding surface of the base component includes features defining localized variations in depth of the projection. Consequently, heat transfer within the base component is subject to localized variations of thermal mass creating localized differences in heat transfer from the molding surface. Known arrangements of heat transfer for such mold components are not effective to accommodate these differences. Hence, there is a continuing need for providing improved heat transfer effectiveness for blow molding articles having concave bases.